Debugging Dynamically Allocated 2D Array with Xcode 5

Question

I've the following C code that creates a dynamically allocated 2D array.

numbersArray = (int **)malloc(sizeof(int *)* primeNumber);

for (i =0 ; i < primeNumber; i++)
    numbersArray[i] = (int *)malloc(sizeof(int)*2);

numbersArray is globally defined and primeNumber is just a number that I calculate during the execution of the program.

My program performs well without problems. I can do various processes on the array. It works totally fine.

My question is that Xcode 5 doesn't show the contents of numbersArray when debugging. It just shows the following:

Debug area in Xcode 5

Why can't it display the dynamically allocated array properly that I would be able to see each and every cell in the array?

I checked similar questions before posting this and they talked about dynamic allocation that the compiler isn't aware of the array size(s) until runtime but I think I remember that before(in previous versions of Xcode) I was able to see the contents of a dynamically allocated array.

What's really going on here? Has it been always like this or is it an Xcode 5 thing or maybe I have the configure Xcode?

Community · Accepted Answer · 2017-05-23 11:58:00Z

1

First, please don't cast the return value of malloc() in C.

Now, I think you mis-remember. Unless it's doing pretty advanced analysis, there should be no way for the debugger to know that an int ** variable should be interpreted as an array of a specific size.

What you can often do, is use various "view memory as ..."-type commands to inspect the memory. This will be even more complicated by the fact that your array is "jagged", i.e. each row is a pointer to that rows's data rather than the entire array being a single contiguous allocation.

edited May 23, 2017 at 11:58

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answered Nov 18, 2013 at 15:42

unwind

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2 Comments

Charlie Burns Over a year ago

OP could check the return value of malloc too.

Can Over a year ago

Yeap, guess I misremember. Thanks for the tip. Also could you please share some commands to inspect the memory. Like how can I inspect a double array?

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